ACCU-Torq and Hostile Duty inverter-duty induction motors

Nidec Motor Corporation sells inverter-duty three-phase induction motors under names such as ACCU-Torq and Hostile Duty, mostly under the US Motors brand. Inverter duty construction uses an insulation system that tolerates the voltage spikes and fast rise times of PWM drives, and bearing protection such as insulated bearings or shaft grounding rings can be used to limit circulating currents. The motors offer wide constant-torque speed range, often 1000:1 with an encoder or 20:1 without, and they are available in NEMA frame sizes with various horsepower ratings. Hostile Duty versions add features for harsh locations, such as heavy cast iron frame, sealed bearings, corrosion-resistant coatings, and extra protection against moisture, dust and chemicals. Efficiency typically meets NEMA Premium levels. Typical applications include pumps, fans, conveyors, compressors, extruders, process lines and machine tools driven by variable frequency drives.